Straight lift pump jack



Nov. 15, 1938. A. J. TRAV IS 2,136,478

STRAIGHT LIFT PUMP JACK Filed NOV. 4, 1937 3 Sheets-Sheet l I I'll ann- F ATTORNEY NOV. 15', A, J T V STRAIGHT LIFT PUMP JACK 2 Sheets-Sheet 2 Filed Nov. 4, 1937 14/10 cf Zak/L9 ATTORNEY Patented Nov. 15, 1938 UNITED 'sTArEf s STRAIGHT L'IFT' PU1\IP JACK Alvin J Travis, Hardesty, 0kla., assignor to Frank E. EvanslDarrouzett, Tex.

Application November 4, 1937, Serial No. 172,701

' 7 Claims. (01.174 31) This application is a continuation inpart of my application Serial No. 721,233, filed April 18,

1934, which later matured into Patent No.;2,011,-= 883, dated August 20, 1935.

This invention relates to a pump operating mechanism or pump jack andmore particularly to a straight lift pump jack as distinguished from the old type walking beam pump jack. 7

Some of the objects of the invention are topro- Vide a device of this class for converting rotary motion into reciprocatory motion; to provide a mechanism having a shiftable pinion which operates a rack bar and yet which is much more efiicient than other mechanisms of this type due to the fact that binding of the intermeshed teeth is substantially eliminated, and that cross pressure on the ends of the rack bar is practically eliminated; to provide a device of this class including a means for partially counterbalancing the weight which the device must lift; and to' provide such a device including means for adjustably limiting the movement of the rack bar in one direction, thus relieving other parts of the device from extreme tension at the time the downward movement of the pump operating rods ceases.

Other objects of the invention will be fully and comprehensively understood from a consideration of the following detailed description when read in connection with the accompanying drawings which form a part of this application. The drawings are to be considered illustrative only.

In the drawings, 7

Figure 1 is a side elevation illustrating'a pump jack constructed in accordance with my iIlVBIl-s tion;

Figure 2 is a side sectional view showing the arrangement of the pinion shiftingmechanism, its pinion, and their positions with relation to the rack bar during the shifting operation;

Figure 3 is a perspective view of the adjustable means for limiting the movement of the rack bar; a

Figure 4 is a side elevation of the shifting roller showing the manner of mounting the gear train on that roller;

Figure 5 is a side view of the opposite side of the shifting roller and the upper end of the rack bar, and shows particularly the cam and roller means for preventing 'the binding of the intermeshed teeth of the shiftable pinion and rack bar;

Figure 6 is a perspective view of the rack bar and its guide member, together with the adjustable means for limiting the movement of the rack bar in one direction; and,

Figure 7 is a front elevation illustrating the pump jack shown in Figure l.

Referring particularly to Figure 1, the working mechanism of the device is supported within a suitable frame, designated as a whole by the numeral l0, and which is composed of side members H, i2, i3 and M, a suitable floor l5, opposed cross braces, all of which are designated by the numeral l6, and a top plate I l;

I prefer to use a two piece bearing block It for supporting and journaling a shifting roller l9. The bearing block l8 may be suitably secured to the forward end of the top plate I! as at 2t, and its lower end may be suitably secured to the upper ends of the members II and i3. The bearing block I8 is rigidly secured in a suitable manner, as by a plurality of screws 21 and 22, to therear wall 23 of a channeled rack bar guide member. Thus the supporting frame I 0 rigidly supports both the bearing block [8 and the rack bar guide member, which is designated as a whole by the numeral 24.

As shown in Figures 2 and 4, the shifting roller l9 journals a drive shaft 25, one end of which extends through the roller l9 and protrudes into a central longitudinal slot 26 in the rack bar 2?, as shown in Figure 6. The shiftingroller also journals a shaft 28,to one end of which is secured a shiftable pinion 29, in a position of alignment with the teeth on the rack bar 27. Between the shiftable'pinion and the shifting roller iii, a guide roller 3i], (Figs. 2 and 5) is carried by the shaft 28, the purpose of which will be later de scribed. On its opposite side the shifting roller i9 carries a bearing plate 3|, which is rigidly secured'to the roller in spaced relation thereto in any suitable manner, as by spacers and stud bolts 32 and 33 respectively. The bearing plate 3i forms a second journal for the shafts 25 and 28, and thus aids in preventing the development of end play in those shafts. Between the bearing plate 3i and the roller IS the shaft 28 carries a gear 34, which is rigidly secured thereto in any suitablemanner, to drive the pinion 29. The drive shaft 25 carries a drive pinion 35 which is in alignment with the gear 34 but which meshes only with an idle piinon 36, as shown in Figure a. The idle pinion in turn meshes with the gear 34.

The shaft 31 on which the idle pinion rotates is rigidly secured to the roller 19 as well as to the bearing plate 3i andldoes not turn with the idle pinion 36. The shifting roller It, on its opposite side, carries a stub shaft 42 which in turn carries a guide roller 43 (Fig. 4) which is adapted to cooperate with the guide roller 30 in a man-;

lit

ner hereinafter described. On the outer end of the drive shaft 25 a suitable pulley 38 may be rigidly secured to be driven by belt or by other means, from a suitable power means 39.

With this arrangement it will be seen that as the drive shaft 25 is rotated, the drive pinion 35 drives the gear 34 in the same direction of rotation, the motion being transmitted through the idle gear 36; also that the rotation of the gear 34 rotates the shiftable pinion 29, which is in mesh with the teeth on the rack bar 21, and the rack bar is moved lengthwise within the guide member 24. It will also be seen that the shifting roller IS, the bearing plate 3|, and all the gears,- rollers, and pinions are shiftable with the shifting roller as it rotates within its bearing block 18 about the drive shaft 25. The actual shifting of the roller l9 takes place only when the ends of the rack bar approach the pinion, 29, this pinion traveling around the toothed arcuate ends of the rack bar as the roller l9 shifts.

Referring now more particularly to Figures 5 and 6 it will be seen that an integral eccentric cam is formed at each end of the rack bar in a position immediately adjacent the teeth thereon. The two cams are designated by the numerals 40 and 4|. The forward guide roller 43, as it is shifted around the end of the rack bar 21, rides the cams 40 and 4| respectively, and by delaying the completion of the shifting of the roller I9 substantially eliminates excessive side pressure on the end of the rack bar. The following guide roller 30, which is concentric with the gear 29, also rides each cam respectively and the eccentric form of the cam serves to partially force the teeth of the gear 29 out of mesh with the end teeth on the rack bar 21, thus preventing binding of these intermeshed teeth as the pinion 23 shifts around the ends of the rack bar.

In Figures 6 and '7 it will be noted that the forward wall of the guide member 24 is provided with a longitudinal slot 44 which is adapted to receive a projecting lug 45 made integral with the rack bar 21. As the rack bar 21 reciprocates within the guide member 24, the lug 45 reciprocates within the slot 44. Any suitable means may be secured to the lug 45 for attaching it to a pump operating cable or rod 46 and to a counterbalance cable 41. The means I have illustrated are simply hooks welded or otherwise suitably secured to the lug.

As a means for partially counterbalancing the weight to be lifted by the device, I provide a pulley support 52 rigidly secured to the top plate I1, and if desired, to the upper end of the guide member 24 in any suitable manner. This pulley support 52 journals a pulley 48, the periphery of which is in alignment with the hooks on the lug 45 on the rack bar. At its other end the support also journals a pulley 49, and over the two pulleys are strung a cable or rope 41 one end of which is attached to the upper hook on the lug 45, and the other end of which is secured to a suitable weight 50. Thus, as the rack bar reciprocates and as the lug 45 moves upward to lift the weight of the pump operating rods 46, the weight 50 tends to pull the rack bar upward, counterbalancing a portion of the weight to be lifted. As the rack bar moves in the opposite direction, the weight of the pump operating rods pulling downward on the lug 45 lifts the weight 50 without the aid of the power means 39.

It will be noticed by a study of Figures 1 and 6 that the guide member 24 has opposed side openlugs, and also has an aligned portion of its rear wall cut away in order to afford contact of the shiftable pinion 29 with the teeth on the rack bar 21. These openings and the cut away portion of the rear wall of the guide member are substantially in alignment with the shifting roller I9, and also serve to afford space for the shifting of the roller and its gear train.

As a means for limiting the movement of the rack bar I prefer to use a bumper 53 (Fig. 3) cut from cylindrical stock, having a substantially reduced intermediate portion made by milling rings on the cylindrical stock, the rings being so spaced as to afford contact with the teeth on the end of the rack bar. This particular shape prevents injury to the teeth of the rack bar. The adjustment of the bumper is made possible by the use of an off-center spindle on which the bumper is journaled by the side walls of the guide member 24. A set screw 5| may be used to prevent accidental turning of the bumper. Any other suitable type bumper may be used, however, and I do not wish to be limited to this particular construction.

While I have described and illustrated a specific embodiment of my invention, I am aware that numerous alterations and changes may be made therein and I do not wish to be limited except by the prior art and the scope of the appended claims.

I claim:

1. In a device of the character described, the combination with a rack bar, toothed on side; and ends, a supported guide member for the rack bar, and a driven shiftable pinion for reciprocate.- bly driving the rack bar, of an eccentric guide cam on each end of the rack bar; and a guide roller rotatably and concentrically mounted on the shaft which carries the shiftable pinion, whereby as the pinion shifts around the ends of the rack bar, the roller contacts the said cams respectively and partially forces the teeth of the pinion away from the end teeth of the rack bar preventing binding and excessive wear of the teeth.

2. In a device of the character described, the combination with a rack bar, toothed on sides and ends, a supported guide member for the rack bar, and a driven shiftable pinion for reciprocatably driving the rack bar, of: an eccentric guide cam on each end of the rack bar; and a freely rotatable roller mounted in advance of the shiftable pinion and shiftable therewith, and adapted to contact the cams at the respective ends of said rack bar to delay the completion of the shifting movement of said shiftable pinion, thus relieving excessive side pressure on the ends of said rack bar and the attendant wear caused by said side pressure.

3. In a device of the character described, the combination with a rack bar, toothed on sides and ends, a supported guide member for the rack bar, and a driven shiftable pinion for reciprocate,- ably driving the rack bar, of a guide roller rotatably and concentrically mounted on a shaft which carries the shiftable pinion; a second roller rotatably mounted in advance of the shiftable pinion and shiftable therewith; and an eccentric guide cam on each end of said rack bar; said first mentioned roller adapted to contact the said cams as the respective ends of the rack bar approach the shiftable pinion, and to force said pinion to shift around the end of the bar in an arc the radius of which is slightly longer than the combined radii of the shiftable pinion and the semi-circular toothed ends of the rack bar,

thus preventing binding and excessive wear of the intermeshed teeth; said second mentioned roller adapted to contact the said cams respectively ahead of the first mentioned roller, to delay the completion of the shifting movement of said shiftable pinion, and thus to relieve excessive side pressure on the ends of the rack bar and the attendant wear caused by said side pres sure.

4. In a device of the character described, the combination with a rack bar toothed on sides and ends, a supported guide member for the rack bar, and a driven shiftable pinion for reciprocatably driving the rack bar, of: an adjustable bumper carried by one end of the rack bar guide member for adjustably limiting the travel of the rack bar in one direction; an eccentric guide cam on each end of the rack bar; and a guide roller rotatably and concentrically mounted on a shaft which carries the shiftable pinion, whereby as the pinion shifts around the ends of the rack bar, the roller contacts the said cams respectively and partially forces the teeth of the pinion away from the end teeth of the rack bar preventing binding and excessive wear of the teeth.

5. In a device of the character described, the combination with a rack bar toothed on sides and ends, a supported guide member for the rack bar, and a driven shiftable pinion for reciprocatably driving the rack bar, of: an adjustable bumper carried by one end of the rack bar guide member for adjustably limiting the travel of the rack bar in one direction; an eccentric guide cam on each end of the rack bar; and a freely rotatable roller mounted in advance of the shiftable pinion and shiftable therewith, and adapted to,

contact the cams at the respective ends of said rack bar to delay the completion of the shifting movement of said shiftable pinion, thus relieving excessive side pressure on the ends of said rack bar and the attendant wear caused by said side pressure.

6. In a device of the character'described, the combination with a rack bar toothed on sides and ends, a supported guide member for the rack bar, and a driven shifta-ble pinion for reciprocatably driving the rack bar, of: an adjustable bumper carried by one end of the rack bar guide member for adjustably limiting the travel of the rack bar in one direction; a guide roller rotatably and concentrically mounted on a shaft which carries the shiftable pinion; a second roller rotatably mounted in advance of the shiftable pinion and shiftable therewith; and an eccentric guide cam on each end of said rack bar; said first mentioned roller adapted to contact the said cams as the respective ends of the rack bar approach the shiftable pinion. and to force said pinion to shift around the end of the bar in an arc the radius of which is slightly longer than the combined radii of the shiftable pinion and the semicircular ends of the rack bar, thus preventing binding and excessive Wear of the intermeshed teeth; said second mentioned roller adapted to contact the said cams respectively ahead of the first mentioned roller, to delay the completion of the shifting movement of said shiftable pinion, and thus to relieve excessive side pressure on the ends of the rack bar and the attendant wear caused by said side pressure.

7. A device of the character described comprising: a reciprocable rack bar having toothed s des and toothed arcuate ends; an eccentric arcuate cam formed integral on each end of said rack bar immediately adjacent the teeth thereon; a channeled hollow guide member in which said rack bar is adapted to reciprocate, said member having opposed intermediate openings through its sides, and an aligned opening through its rear wall; a bearing block rigidly secured to the rear wall of said guide member adjacent the opening therein; a shifting roller journaled in said bearing block in alignment with the opening in the rear wall of said guide member; a driven pinion mounted on one side of said shifting roller in a position to mesh with the teeth on said rack bar through the side and rear wall openings in said guide member, said pinion being shiftable with the shifting roller; a guide roller mounted concentric and immediately adjacent said driven pinion, and adapted to contact said eccentric cams respectively and to thus prevent binding of the meshed teeth as the pinion shifts around the ends of said rack bar; a bearing plate rigidly secured to the opposite side of said shifting roller in spaced relation thereto, the two together'forming a gear train housing; a drive shaft journaled in said bearing plate and in said shifting roller, concentric with the latter; a gear train including a drive shaft pinion mounted within said gear train housing for transmitting movement from said drive shaft to said shiftable pinion, said gear train being shiftable with said shifting roller.

about the drive shaft and its pinion; power means for rotating the drive shaft to reciprocate said rack bar; adjustable means mounted at one end of said guide member in a position to con tact said rack bar to limit its movement in one direction; and means for rigidly supporting said guide member and its associated bearing block.

ALVIN J. TRAVIS. 

